Question

Finding a counter example to one of four formulas for images and inverse images

score 272 · Answer 1 · 2026-04-17 15:16:02

272

Views

Finding a counter example to one of four formulas for images and inverse images

Published on 17 Apr 2026 - 15:16

score 414 · Answer 2 · 2026-04-16 01:26:55

414

Views

Is $f(x) = 3 -\frac{2}{x}$ injective or surjective?

Published on 16 Apr 2026 - 1:26

score 1.4k · Answer 3 · 2026-04-11 10:01:02

1.4k

Views

How to approach this set proof question (Iterative Union/Intersection)

Published on 11 Apr 2026 - 10:01

score 404 · Answer 4 · 2026-04-10 11:01:44

404

Views

Proof of uncountability of irrationals without using completeness of real numbers

Published on 10 Apr 2026 - 11:01

score 46 · Answer 5 · 2026-04-16 14:00:52

46

Views

If every fuction $f:A \mapsto B$ with $A\subseteq B, f(A)=B$ is not injective(1-1) then $A\supset B$

Published on 16 Apr 2026 - 14:00

score 274 · Answer 6 · 2026-04-10 16:37:53

274

Views

Cardinality of Cauchy Sequences in Natural Numbers.

Published on 10 Apr 2026 - 16:37

score 2.1k · Answer 7 · 2026-03-25 12:49:58

2.1k

Views

Prove that union of two equivalences relations is also equivalence relation if and only if that union equals to thier compositions

Published on 25 Mar 2026 - 12:49

score 66 · Answer 8 · 2026-04-15 01:03:30

66

Views

Proving bijection between $\mathcal{P}(\mathbb{R}\times\mathbb{R})$ and $\mathcal{P}(\mathbb{R})$

Published on 15 Apr 2026 - 1:03

score 2.4k · Answer 9 · 2026-04-16 04:40:44

2.4k

Views

Can there be an $\aleph_2$ or even greater?

Published on 16 Apr 2026 - 4:40

score 68 · Answer 10 · 2026-04-15 14:11:30

68

Views

Is this a bijection between $\mathcal{P}(\mathbb{R})$ and $\mathbb{R}^\mathbb{R}$

Published on 15 Apr 2026 - 14:11

score 48 · Answer 11 · 2026-04-13 04:17:06

48

Views

Is the first part of my set theory proof correct?

Published on 13 Apr 2026 - 4:17

score 153 · Answer 12 · 2026-04-10 05:37:12

153

Views

How to find a function to create a proper subset from intersections?

Published on 10 Apr 2026 - 5:37

score 54 · Answer 13 · 2026-04-14 06:02:24

54

Views

Does $\{(-1)^n\mid n\in\mathbb N\}=\{-1,1\}$

Published on 14 Apr 2026 - 6:02

score 85 · Answer 14 · 2026-04-17 02:21:01

85

Views

image and preimage of a function - set theory

Published on 17 Apr 2026 - 2:21

score 184 · Answer 15 · 2026-04-15 18:20:24

184

Views

Demonstration with symmetric difference of sets

Published on 15 Apr 2026 - 18:20

List Question

Finding a counter example to one of four formulas for images and inverse images

Is $f(x) = 3 -\frac{2}{x}$ injective or surjective?

How to approach this set proof question (Iterative Union/Intersection)

Proof of uncountability of irrationals without using completeness of real numbers

If every fuction $f:A \mapsto B$ with $A\subseteq B, f(A)=B$ is not injective(1-1) then $A\supset B$

Cardinality of Cauchy Sequences in Natural Numbers.

Prove that union of two equivalences relations is also equivalence relation if and only if that union equals to thier compositions

Proving bijection between $\mathcal{P}(\mathbb{R}\times\mathbb{R})$ and $\mathcal{P}(\mathbb{R})$

Can there be an $\aleph_2$ or even greater?

Is this a bijection between $\mathcal{P}(\mathbb{R})$ and $\mathbb{R}^\mathbb{R}$

Is the first part of my set theory proof correct?

How to find a function to create a proper subset from intersections?

Does $\{(-1)^n\mid n\in\mathbb N\}=\{-1,1\}$

image and preimage of a function - set theory

Demonstration with symmetric difference of sets

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